(function (Prism) {

    // https://yaml.org/spec/1.2/spec.html#c-ns-anchor-property
    // https://yaml.org/spec/1.2/spec.html#c-ns-alias-node
    var anchorOrAlias = /[*&][^\s[\]{},]+/;
    // https://yaml.org/spec/1.2/spec.html#c-ns-tag-property
    var tag = /!(?:<[\w\-%#;/?:@&=+$,.!~*'()[\]]+>|(?:[a-zA-Z\d-]*!)?[\w\-%#;/?:@&=+$.~*'()]+)?/;
    // https://yaml.org/spec/1.2/spec.html#c-ns-properties(n,c)
    var properties = '(?:' + tag.source + '(?:[ \t]+' + anchorOrAlias.source + ')?|'
        + anchorOrAlias.source + '(?:[ \t]+' + tag.source + ')?)';
    // https://yaml.org/spec/1.2/spec.html#ns-plain(n,c)
    // This is a simplified version that doesn't support "#" and multiline keys
    // All these long scarry character classes are simplified versions of YAML's characters
    var plainKey = /(?:[^\s\x00-\x08\x0e-\x1f!"#%&'*,\-:>?@[\]`{|}\x7f-\x84\x86-\x9f\ud800-\udfff\ufffe\uffff]|[?:-]<PLAIN>)(?:[ \t]*(?:(?![#:])<PLAIN>|:<PLAIN>))*/.source
        .replace(/<PLAIN>/g, function () { return /[^\s\x00-\x08\x0e-\x1f,[\]{}\x7f-\x84\x86-\x9f\ud800-\udfff\ufffe\uffff]/.source; });
    var string = /"(?:[^"\\\r\n]|\\.)*"|'(?:[^'\\\r\n]|\\.)*'/.source;

    /**
     *
     * @param {string} value
     * @param {string} [flags]
     * @returns {RegExp}
     */
    function createValuePattern(value, flags) {
        flags = (flags || '').replace(/m/g, '') + 'm'; // add m flag
        var pattern = /([:\-,[{]\s*(?:\s<<prop>>[ \t]+)?)(?:<<value>>)(?=[ \t]*(?:$|,|\]|\}|(?:[\r\n]\s*)?#))/.source
            .replace(/<<prop>>/g, function () { return properties; }).replace(/<<value>>/g, function () { return value; });
        return RegExp(pattern, flags);
    }

    Prism.languages.yaml = {
        'scalar': {
            pattern: RegExp(/([\-:]\s*(?:\s<<prop>>[ \t]+)?[|>])[ \t]*(?:((?:\r?\n|\r)[ \t]+)\S[^\r\n]*(?:\2[^\r\n]+)*)/.source
                .replace(/<<prop>>/g, function () { return properties; })),
            lookbehind: true,
            alias: 'string'
        },
        'comment': /#.*/,
        'key': {
            pattern: RegExp(/((?:^|[:\-,[{\r\n?])[ \t]*(?:<<prop>>[ \t]+)?)<<key>>(?=\s*:\s)/.source
                .replace(/<<prop>>/g, function () { return properties; })
                .replace(/<<key>>/g, function () { return '(?:' + plainKey + '|' + string + ')'; })),
            lookbehind: true,
            greedy: true,
            alias: 'atrule'
        },
        'directive': {
            pattern: /(^[ \t]*)%.+/m,
            lookbehind: true,
            alias: 'important'
        },
        'datetime': {
            pattern: createValuePattern(/\d{4}-\d\d?-\d\d?(?:[tT]|[ \t]+)\d\d?:\d{2}:\d{2}(?:\.\d*)?(?:[ \t]*(?:Z|[-+]\d\d?(?::\d{2})?))?|\d{4}-\d{2}-\d{2}|\d\d?:\d{2}(?::\d{2}(?:\.\d*)?)?/.source),
            lookbehind: true,
            alias: 'number'
        },
        'boolean': {
            pattern: createValuePattern(/false|true/.source, 'i'),
            lookbehind: true,
            alias: 'important'
        },
        'null': {
            pattern: createValuePattern(/null|~/.source, 'i'),
            lookbehind: true,
            alias: 'important'
        },
        'string': {
            pattern: createValuePattern(string),
            lookbehind: true,
            greedy: true
        },
        'number': {
            pattern: createValuePattern(/[+-]?(?:0x[\da-f]+|0o[0-7]+|(?:\d+(?:\.\d*)?|\.\d+)(?:e[+-]?\d+)?|\.inf|\.nan)/.source, 'i'),
            lookbehind: true
        },
        'tag': tag,
        'important': anchorOrAlias,
        'punctuation': /---|[:[\]{}\-,|>?]|\.\.\./
    };

    Prism.languages.yml = Prism.languages.yaml;

}(Prism));